PROJECT SUMMARY Storage lower urinary tract symptoms (LUTS), which include urinary urgency, frequency, nocturia, painful urination, and bladder pressure/discomfort, refer to patient experiences when the bladder is unable hold urine appropriately. These highly prevalent symptoms are chronic and debilitating, substantially degrading physical activity and quality of life. Yet despite the heavy burden of storage LUTS on public health, little is understood of the pathophysiology of these symptoms, limiting diagnosis, treatment, and prevention options. Humans harbor diverse microbial communities that live in symbiosis with healthy hosts but are frequently altered in disease. The role of these alterations is unclear, but mounting research suggests that microbial components may interact with human tissue to alter organ function, tissue permeability, and even central nervous system responsivity. We and others have used novel, state-of-the-art DNA sequencing methods to identify bacteria and fungi residing within the urinary tract and describe global differences in urinary microbial communities in patients with storage LUTS. We have yet to understand how these differences impact bladder pathophysiology, but our preliminary data suggest that shifts in these microbial communities underlie or reflect storage LUTS symptoms and correlate with increased local and systemic inflammation. We postulate that interactions of these changed communities with the host alter local and systemic inflammation and increase immunologic activation of bladder urothelial cells, generating inflammatory signatures characteristic of specific urinary symptoms. Based on similarities to other inflammatory diseases, we hypothesize that this inflammation becomes pathogenic in susceptible hosts with dysregulated microbial recognition, possibly mediated by genetic differences in host responsiveness to microbial components. Using state-of-the-art microbial profiling techniques, we will identify changes in urinary bacterial and fungal communities linked to storage LUTS in patients. We will also identify disease-associated variations in inflammatory markers and urothelial activation and associate these findings with specific microbial signatures and symptom patterns. We will perform a targeted characterization of genetic polymorphisms associated with dysregulated inflammatory responses to microbes to explore the contribution of host susceptibility in these conditions. Few previous studies have examined the urinary microbiota; this proposal is the first to integrate multi-omic datasets with clinical metadata to allow the discovery of clinically useful disease markers, microbial and inflammatory, and place them into the context of disease mechanisms and host risk factors. This study may promote a more comprehensive understanding of storage LUTS pathogenesis, identifying the molecular pathways that could serve as targets of new therapeutic agents. Positive results from this study would have significant implications for IC/PBS diagnosis and treatment and provide an important starting point for further studies examining the pathophysiology of this challenging and refractory disease.